This section of DiscoverTheNetworks examines the history of immigration to the United States; public opinion about immigration and immigrants; the evolution of America's immigration policies; the distinguishing characteristics of various immigrant populations in America; and the implications of all the above.

Journalist Ben Jonson notes that prior to 1965, despite some changes in the 1950s, America was a low-immigration country basically living under immigration laws that had been written in 1924. Between the Twenties and the Sixties, the U.S. became a fundamentally middle-class society, and its many European ethnic groups were brought together into a common national culture.

Then the Immigration and Nationality Act of 1965 abolished the national-origins quota system that had regulated the ethnic composition of immigration in fair proportion to each group's existing presence in the population. Those who advocated this new legislation did not acknowledge the consequences of the changes it would produce.

Average immigration levels before the 1965 amendments took effect hovered around 300,000 per annum. By 1996, fully 1,045,000 new legal immigrants were settling in American cities each year.

In 1965 Ted Kennedy stated, "No immigrant visa will be issued to a person who is likely to become a public charge." However, immigrants as a whole receive public assistance at rates far higher than those of native Americans. Political refugees today qualify for such assistance immediately upon setting foot on U.S. soil.

Immigration expert Steven Camarota, Director of Research at the Center for Immigration Studies, has pointed out that as of 2007:

America's immigrant population (legal and illegal) had reached a record of 37.9 million;

Immigrants accounted for one in eight U.S. residents, the highest level in 80 years;

Nearly one-third of all immigrants were illegal aliens, including half of Mexican and Central American immigrants and one-third of South American immigrants;

Since 2000, 10.3 million immigrants had arrived in the U.S. -- the highest seven-year period of immigration in American history -- and more than half of the post-2000 arrivals (5.6 million) were estimated to be illegal aliens;

Of adult immigrants, 31 percent had not completed high school, compared to 8 percent of native-born Americans;

Since 2000, immigration had increased the number of workers without a high-school diploma by 14 percent, and all other workers by 3 percent;

The proportion of immigrant-headed households using at least one major welfare program was 33 percent, compared to 19 percent for native households;

The poverty rate for immigrants and their U.S.-born children (under 18) was 17 percent, nearly 50 percent higher than the rate for natives and their children;